DELTA DUST contains the active ingredient deltamethrin which is the first and only 100% waterproof insecticide dust, that means it works in the wet and damp places that insects frequently seek for a source of water. Nothing short of moving water will disturb it. That makes Delta Dust the ideal crack and crevice treatment. Whether moisture is present in trace or large amounts, it is the insecticide if choice in those difficult areas. Just one application of Delta Dust will remain effective killing insects for up to an amazing 8 months.